Fuel system of internal combustion engine

ABSTRACT

A fuel system of an internal combustion engine comprising a high-pressure pump with a governing element in the form of a rack, and a discharge valve. Said high-pressure pump is connected with a closed-type fuel injector by a high-pressure pipe. For maintaining a high initial pressure in said pipe, it communicates with an accumulator by a pipe via a fuel distributor in the form of a groove and inlet and outlet holes. Pressure in the accumulator is built up by an auxiliary pump. The required high pressure in the accumulator is maintained by a controllable reducing valve communicating with said accumulator.

Leonov et al.

[11] 3,818,882 [4 June 25, 1974 FUEL SYSTEM OF INTERNAL COMBUSTIONENGINE Inventors: Oleg Borisovich Leonov,

Ladozhskaya ulitsa, 2/37, kv. 20; Viktor Viktorovich Arapov, ulitsaChistye Prudy, l l, kv. 52, both of Moscow; Vladimir GrigorievichPavljukov, ulitsa Serova, 5, kv. 8, Zhukovsky Moskovskoi oblasti;Nikolai Nikolaevich Patrakhaltsev, bulvar Yanisa Rainisa, l8, korpus I,kv. 99, Moscow; Nikolai Nikolaevich Manuilov, Leninsky prospekt, 3, kv.163, Moscow; Nikolai Konstantinovich Soldatov, Dnepropetrovskaya ulitsa,5, korpus 4, kv. 178, Moscow, all ofU;S.S.R.-

123/139 AA; 139 BA', {59 AY, 140 ML References Cited UNITED STATESPATENTS 2,078,286 4/1937 Seagren l23/l39 R FOREIGN PATENTS ORAPPLICATIONS 512.490 7/1932 Germany 123/139 AT Primary ExaminerLaurenceM. Goodridge Attorney, Agent, or Firm-Eric H. Waters [5 7] ABSTRACT Afuel system of an internal combustion engine comprising a high-pressurepump with a governing element in the form of a rack, and a dischargevalve. Said highpressure pump is connected with a closed-type fuelinjector by a high-pressure pipe. For maintaining a high initialpressure in said pipe, it communicates with an accumulator by a pipe viaa fuel distributor in the form of a groove and inlet and outlet holes.Pressure in the accumulator is built up by an auxiliary pump. Therequired high pressure in the accumulator is maintained by acontrollable reducing valve communicating with said accumulator.

4 Claims, 2 Drawing Figures PATENTEEJUNZS am SHEET 2 BF 2 L Yi.

WHH

FIBZ

The present invention relates tointemal combustion engines and morespecifically it relates to the fuel sys tems of internal combustionengines.

The present invention can be utilized most successfully in Dieselengines with open combustion chambers, particularly'in the Dieselengines running continuously under partial loads and unsteady-stateconditions, i.e., mainly in the transport engines.

The overwhelming majority of the existing fuel systems of internalcombustion engines consists of a highpressure fuel pump, for example ofa plunger type, driven by a cam and provided with a discharge valve witha suction collar. Besides, this system comprises a closed-type fuelinjector connected to the highpressure fuel pump by a high-pressurepipe.

The suction collar of the discharge valve relieves pressure in thehigh-pressure pipe after .injection. A certain residual pressure in thehigh pressure pipe serves at the same time as initial pressure for thesubsequent cycle of fuel injection. This initial pressure determines toa considerable extent the fuel supply characteristic and the performanceof the engine proper.

However, such a fuel system fails to ensure sufficient stability of theresidual pressure in the high-pressure pipe from one cycle to another aswell as in the highpressure pipes of a multiple-cylinder engine; as aconsequence, the fuel supplyis unstable which reduces considerably theengine economy, particularly at duties other than nominal.

The instability of residual pressure in the highpressure pipe exerts aparticularly conspicuous influence on the functioning of the fuel systemat low engine loads and speeds. This denies the possibility of reducingthe minimum stable engine speed and increases the irregularity ofcrankshaft rotation which is most objectionable in Diesel-generatorsets.

The residual pressure in thehigh-pressure pipe of this fuel system isset only for one engine duty, usually the I nominal one. While theengine is running at various duties, the residual pressure in thehigh-pressure pipe varies within wide limits even to a residual vacuumwhich cuts down the engine efficiency and power.

During unsteady-state operation of the engine such a fuel system ischaracterized byhigh residual pressures accompanied by additional fuelinjection into the engine cylinders, which increases the temperature ofexhaust gases, causes smoking at the exhaust and reduces the reliabilityand durability of the fuel injectors and the engine as a whole.

The starting of the engine with such a fuel system is characterized byinefficient injection and distribution of fuel throughout the combustionchamber which impairs starting and causes a low crankshaft speed and alow residual pressure of fuel in thehigh-pressure pipe at the initialstage of starting.

Changing the residual pressure in the high-pressure pipe is one of theways towards stepping up the economy, efficiency, reliability anddurability of the engine.

the high-pressure pipe within the entire range of engine speeds andloads. Such a fuel system comprises a highpressure fuel pump with agoverning element and a dis- 2 charge valve. The high-pressure pump iscommunicated by a high-pressure pipe with a closed-type fuel injector.In order to maintain a high initial pressure in the high-pressure pipe,the latter is connected with an accumulator via a fuel distributor and apipe. Pressure in the accumulator is built up by an auxiliary pump andis maintained constant by a reducing valve at all engine duties. Thefuel distributor controls the filling of the high-pressure pipe atpredetermined moments of time before the beginning of each cycle ofinjection.

A disadvantage of such a fuel system lies in the impossibility ofcontrolling the initial pressure in the highpressure pipe on changes inthe engine duty.

As has been shown by experiments, maximum economy of the engine atvarious speeds and loads will be reached if the above-mentioned initialpressure changes simultaneously with the changes in the speed of theengine crankshaft and in the position of the governing element of thehigh-pressure pump. To achieve a higher engine power both understeadyand unsteady-state conditions, it is practicable that the initialpressure in the high-pressurepipe should be increased above the limitwhich ensures a high engine economy.

During engine starting such a fuel system fails to create an initialpressure in the high-pressure pipe which would be higher than thatensured for all the engine duties; it means that this fuel system is notsuitable for increasing greatly the reliability of engine starting.

An object of the present invention is to raise the engine economy.

Another object of the invention is to increase engine power.

Still another object of the invention is to increase the reliability andextend the service life of the fuel system and the engine as a wholeunder the conditions of maximum economy.

One more object of the invention is to improve engine economy and powerunder unsteady-state operating conditions.

And still another object of the invention is to increase the reliabilityof engine starting. The last object of the invention is to reduce theminimum stable speed of the engine crankshaft.

in accordance with these and other objects we hereby provide a fuelsystem of internal combustion engine comprising a high-pressure pumpwith a governing element and a discharge valve, connected with aclosed-pipe fuel injectors by a high-pressure pipe in which a highinitial pressure is maintained by connecting it via a fuel distributorand a pipe with an accumulator where a high pressure is built up by anauxiliary pump wherein, according to the invention, there is acontrollable reducing valve connected with the accumulator formaintaining in it a required high pressure.

This fuel system builds up and maintains automatically a high initialpressure in the high-pressure pipe located between the discharge valveand the fuel injector. This raises the economy, reliability anddurability of the engine by increasing the operational stability of thefuel system, improving the automization of fuel and its distributionover the combustion chamber of the engine. I

It is practicable that the controllable reducing valve should consist ofa body with fuel inlet and outlet channels, said body accommodating arotatable bushing whose outlet hole is aligned with a fuel outletchannel in the body, said bushing being provided with a turning valveelement loaded by a fuel pressure at one end and by a spring at theopposite end and connected by a gear rim with the rack of thehigh-pressure fuel pump, said bushing meshing by means of a gear rimwith the rack of a governor which reacts to the changes in the rotationspeed of the engine crankshaft.

The controllable reducing valve of this design controls automaticallythe initial pressure in the highpressure pipe and maintains it either ata level ensuring a high engine power or at a level providing for a highengine economy; the initial pressure is controlled in accordance withtwo parameters, i.e., engine load and speed.

At the minimum engine speed this valve builds up and maintainsautomatically such an initial pressure which increases the stability offuel supply at this speed, thus ensuring a reduction in the minimumsteady engine speed.

Besides, it changes the initial pressure during unstable operationthereby improving the economy and' power of the engine at this duty.

During engine starting this valve creates an initial pressure ensuringmaximum reliability of starting.

In addition, such a design of the controllable reducing valve diminishesthe pressure control force in the accumulator and, consequently, theforce required for controlling the initial pressure in the high-pressurepipe.

It is recommended that the valve element should be made in the form of acylindrical slide valve with a shaped edge facing the fuel inlet channelin the body.

Such a construction of the cylindrical slide valve increases theaccuracy of adjusting pressure in the accumulator and, consequently, theinitial pressure in the high-pressure pipe, and widens the field ofapplication of the controllable reducing valve in the engines designedfor various purposes because changes in the outline of the shaped edgeof the slide valve bring about corresponding changes in the control ofthe initial pressure.

It is preferable that the fuel inlet channel in the body of thecontrollable reducing valve should accommodate an immovable bushingentering the rotatable bushing and forming, together with the latter, aprecision pair.

Owing to this method of sealing the rotatable bushing is relieved of theaxial component of the fuel pressure.

This improves the accuracy of controlling the initial pressure in thehigh-pressure pipe and reduces the irregularity of governing thecrankshaft speed.

The fuel system according to the invention, employed in a four-strokesix-cylinder supercharged Diesel with an open combustion chamber, anominal speed of 1,500 rpm, a minimum steady speed of 500 rpm, a nominalpower of 250 hp, a maximum torque of 130 kgm at l,200 rpm, a specificfuel consumption of I68 g/BHP-hr at a nominal speed and 220 g/BI-lP-hrat a minimum speed reduces the minimum steady speed of the engine to 250rpm, the specific fuel consumption at the nominal speed to 162 g/BHP-hrand at the minimum speed to 207 g/BHP-hr, increases the maximum torqueto 144 kgm at 1,100 rpm, ensures a constant power within the enginespeed range from 1100 to 1500 rpm and reduces the acceleration time ofthe Diesel with electric generator 1.6 1.8 times depending on the load.

Other objects and advantages of the invention will become apparent fromthe detailed description that follows and from the accompanyingdrawings, in which:

FIG. 1 is a diagrammatic view of a fuel system of an internal combustionengine, according to the invention;

FIG. 2 is a longitudinal section of the controllable reducing valve inthe closed position.

The fuel system of a Diesel engine 1 (FIG. 1) comprises a high-pressurefuel pump 2 driven by a cam 4 of a camshaft 3 and an auxiliary pump 5driven by a cam 6 of the camshaft 3. The high-pressure fuel pump 2 has adischarge valve 7 with a sealing seat 8 and a suction collar 9. The pump2 is connected by a highpressure pipe 10 with a closed-type fuelinjector 11 installed on the Diesel 1. The auxiliary pump 5 has adischarge valve 12 and a plunger 13 and is connected by a pipe 14 withan accumulator 15. The pumps 2 and 5 are connected by a pipe 16 with apump 17 which tops up a tank 18 to compensate for the fuel used up bythe pumps 2 and 5. Thefuel pressure in the accumulator is controlled bya reducing valve 19 (FIG. 2) which receives fuel from the accumulator 15through a pipe 20 and from which the fuel is discharged through a pipe21 into the tank 18. The accumulator 15 is connected by a pipe 22 with afuel distributor which is made in the form of a groove 23 on a plunger24 of the pump 2, and of inlet 25 and outlet 26 holes in a bushing 27. Achannel 28 communicates the pipe 22 with the inlet hole 25. The outlethole 26 is connected with the high-pressure pipe 10 through the channel29.

The controllable reducing valve 19 is connected by a rack 30 with agovernor 31 while a rack 32 connects it with the rack 33 of thehigh-pressure fuel pump 2.

The controllable reducing valve 19 (FIG. 2) com prises a body 34 withfuel inlet and outlet channels 35 and 36. Inside the body 34 there is arotatable bushing 37 with an outlet hole 38. The hole 38 is incommunication with the channel 36. The rotatable bushing 37 accommodatesa valve element in the form of a cylindrical slide valve 39 which formsa precision pair with said bushing. The slide valve 39 has a shaped edge40 facing the fuel inlet channel 35 and is subjected to fuel pressure atone end while at the other end it is loaded, via a sleeve 41 by a spring42 resting on an adjustable nut 43, the latter being used forpretensioning the spring 42. The fuel inlet channel 35 accommodates animmovable bushing 44 which enters the rotatable bushing 37, forming aprecision pair with the latter.

A pin 45 of the slide valve 39 enters the axial slots 46 of a rotatablegear 47 whose teeth are in mesh with the teeth of the rack 32 (FIG. 1)which, in turn, meshes with the rack 33 of the high-pressure fuel pump2. The upper part of the rotatable bushing 37 (FIG. 2) is provided witha gear rim 48 whose teeth mesh with the teeth of the rack 30 (FIG. 1) ofthe governor 31 which reacts to the changes in the rotation speed of theDiesel engine 1.

The fuel system of the Diesel engine functions as follows.

Engine starting.

When the crankshaft of the Diesel 1 (FIG. 1) is rotated at starting, therack 33 of the high-pressure fuel pump 2 occupies the extreme rightposition which corresponds to zero fuel delivery to the combustionchamher (not shown in the drawing) of the Diesel 1. During this periodthe fuel is delivered from the tank 18 by the pump 17 through the pipe16 into the spaces above the plungers of the high-pressure pump 2 andauxiliary pump 5. I

The camshaft 3 driven by the crankshaft (not shown in the drawing) ofthe Diesel 1 operates the plunger 13 of the pump 5 by its cam 6 whileits cam 4 actuatesthe plunger 24 of the pump 2. The plunger 13 goes up,delivering fuel through the valve 12 and pipe 14 into the accumulator15. From the accumulator 15 the fuel flows through the pipe 22into thechannel 28 of the high-pressure pump 2 and enters the controllablereducing valve 19 through the pipe 20.

In the valve 19 the fuel enters the channel 35 (FIG. 2) of the immovablebushing 44 and the space of the rotatable bushing 37 above the end ofthe slide valve 39 and its shaped edge 40. When the axial force of thefuel pressure applied to the end of the slide valve 39 exceeds the forceapplied by the spring 42 to the slide valve 39 via the sleeve 41, theslide valve 39 starts moving down. The beginning'of the downwardmovement of the slide valve 39-under the effect of the fuel pressureapplied to its end depends on the degree of pretensioning of the spring42. The shaped edge 40 of the slide valve opens the hole 38 in therotatable bushing 37 through which the fuel is returned into the tank 18(FIG. 1) through the channel 36 (FIG. 2) and pipe 21 (FIG. I). Thepressure at which the shaped edge 40 of the slide valve 39 startsopeningthe hole 38 (FIG. 2) depends on the length of the generatrix between theshaped edge 40 of the slidevalve 39 and the hole 38 and on thecharacteristic of the spring 42. It means that the stiffer the springand the longer the generatrix be.- tween the shaped edge 40 and the hole38, the higher pressure will have to be applied to the end of the slidevalve to start the discharge of fuel from the accumulator 15 (FIG. 1).

As a result of the fuel discharge, pressure in the accumulator 15 drops,the axial force of the pressure on the end of the slide valve 39 (FIG.2) is reduced too. Then the force of the spring 42 will exceed the forceof the fuel pressure applied to the end of the slide valve 39, thelatter will go upward and close the hole 38 in the rotatable bushing 37.

Thus, a required fuel pressure will be reached in the accumulator 15(FIG. 1).

After the plunger 24 has come to the downmost position, the fuel at thepredetermined pressure will flow from the accumulator 15 through thepipe 22 and channels 28 and 29 into the high-pressure pipe 10 via theholes 25 and 26 in the bushing 27 and via the groove 23 on the plunger24.-

Hence, the predetermined initial pressure will be ensured in thehigh-pressure pipe 10. The system is prepared for engine starting.

The rack 33 of the high-pressure pump 2 moves Thus, the residualpressure in the pipe 10 either becomes lower than in the known systemsor even drops to a vacuum.

The plunger 24 moves down. As soon as it comes to the downmost position,a new cycle of preparing the fuel system for injection is startedbybuilding up a high initial pressure in the high-pressure pipe 10.

Changes in engine operating duty.

If the engine load increases, the rack 33 of the highpressure fuel pump2 moves along arrow A thus in creasing the amount of fuel supplied intothe Diesel 1 while the rack 32 of the controllable reducing valve 19(connected with the rack 33) turns the gear 47 (FIG. 2). The gear 47turns the slide valve 39 along arrow B with the aid of the slots 46 andthe pin 45.

The length of the generatrix of the cylindrical slide valve from theedge 40 to the hole 38 changes in accordance with the outline of theshaped edge 40 of the slide valve 39. Hence, the travel of the slidevalve 39 to the moment of opening of the hole 38 by the shaped edge 40is increased in accordance with the outline of said shaped edge 40. p

In accordance with the characteristic of the spring 42 there will be anincrease in the fuel pressure applied to the end of the slide valve 39at which the hole 38 in the rotatable bushing 37 will open and dischargethe fuel from the accumulator 15 (connected by the pipe 20 with thevalve 19) into the tank 18 (FIG. I) through the channel 36 (FIG. 2) andthe pipe 21 (FIG. 1).

Thus, the fuel pressure in the accumulator 15 will become higher than itwas before the: change in the engine load while the pressure in thehigh-pressure pipe 10 will settle at a new normal level.

If, for example, the speed of the-Diesel l is increased, the governor 31will move the rack 30 along arrow C (FIG. 2). The rack 30 (FIG. 1) willturn the bushing 37 via the gear rim 48 (FIG. 2) of the rotatablebushing 37 against the direction of arrow B. The hole 38 in therotatable bushing 37 will be displaced relative to the slide valve 39 sothat the length of the generatrix of the cylindrical slide valve 39 fromthe shaped edge 40 to the hole 38 will be increased and so will be thelength of travel of the slide valve 39 to the moment when the shapededge 40 opens the hole 38.1171 accordance with the characteristic-of thespring 42 there will be an increase in the fuel pressure applied to theend of the slide valve 39 at which the hole: 38 in the rotatable bushing37 will open and discharge the fuel from the accumulator 15 (FIG. 1)connected by the pipe 20 with the valve 19 into the tank 18 through thechannel 36 (FIG. 2) and the pipe 21 (FIG. 1).

Thus, the pressure in-the accumulator 15 will settle at a higherlevel'than it was before the increase in the engine speed while thepressure in the high-pressure pipe 10 will come to a new predeterminedinitial value.

The fuel system of the Diesel engine according to the invention employsa manual drive connected to the rack 30 (FIG. 1) by any commonly knownmethod.

In this version of the system the governor 31 is omitted. This design ofthe system provides for a higher engine power at various steady andunsteady operational v duties, at the same time retaining the setting ofthe controllable reducing valve for obtaining maximum engine economyunder various loads.

' ducing valve 19.

In this case the rack 33 of the high-pressure fuel pump 2 isdisconnected from the rack 32. This version of the fuel system retainsthe economy of the engine at changes in its speed while higher power ofthe engine at changes in its load is obtained by a manual control leveractuating the controllable reducing valve 19.

The functioning of the fuel system in this case is similar to thatdescribed above at changes in the engine load.

The fuel system of an internal combustion engine according to theinvention increases the economy and power of the engine under varioussteady and unsteady operating conditions, reduces the minimum stablecrankshaft speed, improves the reliability and promptness of startingand ensures a constant power characteristic within the speed range fromthe rated to twothirds rated value.

What is claimed is:

l. A fuel system of an internal combustion engine comprising, incombination, a high-pressure fuel pump; an accumulator; an auxiliarypump communicating with said accumulator for building up pressure withinsaid accumulator; a controllable reducing valve communicating with saidaccumulator and maintaining a pre-determined high pressure in saidaccumulator; a closed-type fuel injector; a high-pressure pipeconnecting said closed-type fuel injector with said highpressure fuelpump; a fuel distributor; a fuel pipe connecting said accumulator withsaid high-pressure pipe through said fuel distributor for maintaining asubstantially high initial pressure in said high-pressure pipe.

2. A fuel system of an internal combustion engine comprising, incombination, a high-pressure fuel pump with governor; an accumulator; anauxiliary pump communicating with said accumulator for building uppressure within said accumulator; a controllable reducing valvecommunicating with said accumulator and maintaining a pre-determinedhigh pressure in said accumulator', a closed-type fuel injector; ahigh-pressure pipe connecting said closed-type fuel injector with saidhigh-pressure fuel pump; a fuel distributor; a fuel pipe connecting saidaccumulator with said high-pressure pipe through said fuel distributorfor maintaining a substantially high initial pressure in saidhigh-pressure pipe, said controllable reducing valve comprising a bodywith fuel inlet and outlet channels, said body having a rotatablebushing with outlet hole aligned with the fuel outlet channel of saidbody, said bushing having a rotating valve element loaded by fuelpressure at one end, a spring for loading the other end of said valveelement, a gear rack on said fuel pump, a first rim gear connecting saidvalve element with said gear rack, a gear rack on said governor, and asecond rim gear connecting said bushing to said rack on said governor,said governor reacting to changes in the engine speed.

3. A fuel system of an internal combustion engine according to claim 2,wherein said rotating valve element comprises a cylindrical slide valvewith a shaped edge facing said fuel inlet channel in said body.

4. A fuel system of an internal combustion engine ac-.

cording to claim 2, wherein said fuel inlet channel of said body has animmovable bushing entering said rotatable bushing.

1. A fuel system of an internal combustion engine comprising, incombination, a high-pressure fuel pump; an accumulator; an auxiliarypump communicating with said accumulator for building up pressure withinsaid accumulator; a controllable reducing valve communicating with saidaccumulator and maintaining a predetermined high pressure in saidaccumulator; a closed-type fuel injector; a high-pressure pipeconnecting said closed-type fuel injector with said high-pressure fuelpump; a fuel distributor; a fuel pipe connecting said accumulator withsaid high-pressure pipe through said fuel distributor for maintaining asubstantially high initial pressure in said high-pressure pipe.
 2. Afuel system of an internal combustion engine comprising, in combination,a high-pressure fuel pump with governor; an accumulator; an auxiliarypump communicating with said accumulator for building up pressure withinsaid accumulator; a controllable reducing valve communicating with saidaccumulator and maintaining a pre-determined high pressure in saidaccumulator; a closed-type fuel injector; a high-pressure pipeconnecting said closed-type fuel injector with said high-pressure fuelpump; a fuel Distributor; a fuel pipe connecting said accumulator withsaid high-pressure pipe through said fuel distributor for maintaining asubstantially high initial pressure in said high-pressure pipe, saidcontrollable reducing valve comprising a body with fuel inlet and outletchannels, said body having a rotatable bushing with outlet hole alignedwith the fuel outlet channel of said body, said bushing having arotating valve element loaded by fuel pressure at one end, a spring forloading the other end of said valve element, a gear rack on said fuelpump, a first rim gear connecting said valve element with said gearrack, a gear rack on said governor, and a second rim gear connectingsaid bushing to said rack on said governor, said governor reacting tochanges in the engine speed.
 3. A fuel system of an internal combustionengine according to claim 2, wherein said rotating valve elementcomprises a cylindrical slide valve with a shaped edge facing said fuelinlet channel in said body.
 4. A fuel system of an internal combustionengine according to claim 2, wherein said fuel inlet channel of saidbody has an immovable bushing entering said rotatable bushing.